pat 1154 Vertex Coloring (图的简单模拟)

1154 Vertex Coloring (25分)

A proper vertex coloring is a labeling of the graph's vertices with colors such that no two vertices sharing the same edge have the same color. A coloring using at most k colors is called a (proper) k-coloring.

Now you are supposed to tell if a given coloring is a proper k-coloring.
Input Specification:

Each input file contains one test case. For each case, the first line gives two positive integers N and M (both no more than 10​4​​), being the total numbers of vertices and edges, respectively. Then M lines follow, each describes an edge by giving the indices (from 0 to N−1) of the two ends of the edge.

After the graph, a positive integer K (≤ 100) is given, which is the number of colorings you are supposed to check. Then K lines follow, each contains N colors which are represented by non-negative integers in the range of int. The i-th color is the color of the i-th vertex.
Output Specification:

For each coloring, print in a line k-coloring if it is a proper k-coloring for some positive k, or No if not.
Sample Input:

10 11
8 7
6 8
4 5
8 4
8 1
1 2
1 4
9 8
9 1
1 0
2 4
4
0 1 0 1 4 1 0 1 3 0
0 1 0 1 4 1 0 1 0 0
8 1 0 1 4 1 0 5 3 0
1 2 3 4 5 6 7 8 8 9

思路

本题就是每个点有不同颜色， 题意需要找到一个特殊结构满足相邻边的颜色不能相同，如果存在这种情况，就输出这个图结构一共有多少种颜色，如果相邻边的
颜色相同，则输出No
本题邻接矩阵容易超时，因此改用邻接表
直接将每个点的邻接点都判断一次， 如果存在相同颜色的点就输出no

代码

#include<bits/stdc++.h>
using namespace std;
const int maxsize = 1e4 + 5;
//int edge[maxsize][maxsize];
vector<vector<int> > edge;
int main()
{
    int n, m;
    scanf("%d%d", &n, &m);
    edge.resize(n + 1);
    int from, to;
    for(int i = 0; i < m; i++) {
        scanf("%d%d", &from, &to);
        edge[from].push_back(to);
        edge[to].push_back(from);
    }
    int k, color[n];
    scanf("%d", &k);
    set<int> s;
    while(k--) {
        s.clear();
        for(int i = 0; i < n; i++) {
            scanf("%d", &color[i]);
            s.insert(color[i]);
        }
        bool isColor = true;
        for(int i = 0; i < n && isColor; i++) {
            for(int j = 0; j < edge[i].size(); j++) {
                if(color[i] == color[edge[i][j]]) {
                    isColor = false;
                }
            }
        }
        if(isColor)
            printf("%d-coloring\n", s.size());
        else
            printf("No\n");
    }
    return 0;
}